Nasal flap preservation in endoscopic dacryocystorhinostomy for nasolacrimal duct obstruction

AIM:To compare surgical outcomes between the conventional endoscopic dacryocystorhinostomy(DCR)and a modified endoscopic DCR for the treatment of nasolacrimal duct obstruction(NLDO),and evaluate factors associated with the surgical success rate.METHODS:Medical records of patients who underwent primary DCR surgery between January 2016 and July 2020 at the Otorhinolaryngology Department of Eye and Ear International Hospital,Lebanon were reviewed.RESULTS:The study group consisted of 50 consecutive modified endoscopic DCR and the control group consisted of 138 consecutive conventional endoscopic DCR.The success rates at 1y were 98.0%(49 out of 50)for modified DCR,significantly higher compared to 84.8%(117/138)for the conventional DCR;there was no significant difference in the success rate throughout the years in terms of both surgical techniques.The modified surgery vs traditional[adjusted odds ratio(aOR)=14.96]and having an adjunctive septoplasty surgery vs not(aOR=3.99)were significantly associated with higher odds of success.CONCLUSION:Mucosal flap preservation and apposition shows significant improvement in the surgical success rate.Moreover,there is no statistically significant difference found in terms of complication rate and mean operative time between the conventional and the modified techniques.

Endoscopic dacryocystorhinostomy with bicanalicular silicone tube intubation for treating chronic dacryocystitis secondary to nasolacrimal duct stent incarceration

AIM:To investigate the feasibility of endoscopic dacryocystorhinostomy(En-DCR)with bicanalicular silicone tube intubation for treating chronic dacryocystitis secondary to nasolacrimal duct stent(NDS)incarceration.METHODS:En-DCRs were performed on 44 chronic dacryocystitis patients(46 eyes)secondary to NDS incarceration from April 2016 to October 2022.The granuloma and scar tissues were separated,and the removal of NDS incarceration was achieved during the surgery;the flap of the lacrimal sac was trimmed and anastomosed with nasal mucosal,a bicanalicular silicone tube was implanted,and lacrimal size and condition were assessed.The tube was removed 3mo after surgery.During the final follow-up of 12mo when the surgery was completed,the complications and the rates of surgical success were assessed.RESULTS:This study covered 40 patients(42 eyes).Intraoperatively,it was found that the lacrimal sac became small,and the sac wall had granulation and scar tissue attached to the incarcerated NDS in all eyes.At 12mo after surgery completed,the rates of the functional and anatomical success reached 80.95%(34/42)and 83.33%(35/42),respectively.Under the effect of intranasal ostial closure,seven eyes failed to achieve anatomical success.No serious complications(e.g.,visual impairment,sinusitis,and orbital fat prolapse)was observed.CONCLUSION:With the success rate over 80%and no serious complications,En-DCR with bicanalicular silicone tube implantation is effective in treating chronic dacryocystitis secondary to NDS incarceration.

A comparison between monocanalicular and pushed monocanalicular silicone intubation in the treatment of congenital nasolacrimal duct obstruction

AIM: To compare the success rate of monocanalicular versus pushed monocanalicular silicone intubation(PMCI)of the nasolacrimal duct for congenital nasolacrimal duct obstruction(CNLDO).METHODS: In a prospective randomized clinical trial 53 eyes of 49 patients with CNLDO underwent either monocanalicular silicone intubation(MCI)(n =28 eyes) or PMCI(n =25 eyes). All procedures were performed by 1oculoplastic surgeon. Treatment success was defined as the complete resolution of epiphora at 3mo after tube removal.RESULTS: The surgical outcome was assessed in 20 eyes with MCI and 20 eyes with PMCI. The mean age of treatment was 26.25 ±10.08mo(range, 13-49mo) for MCI and 26.85±12.25mo(range, 16-68mo) for PMCI. Treatment success was achieved in 18 of 20 eyes(90.0%) in the MCI group compared with 10 of 20 eyes(50%) in the PMCI group(P =0.01). In the PMCI group, the tube loss(30%)was greater than the MCI group(5%), however the differences between the 2 groups proved to be not significant(P =0.91).CONCLUSION: Our results indicate that MCI has higher success rate in CNLDO treatment compared with PMCI in this small series of patients.

Bicanalicular versus monocanalicular intubation after failed probing in congenital nasolacrimal duct obstruction

AIM：To investigate the clinical outcomes of different intubation techniques in the cases of failed primary probing.METHODS： This retrospective study was performed on338 patients with the diagnosis of congenital nasolacrimal duct obstruction with age 1-4y that had failed primary probing.Intubation was performed under light sedation in operating room and the stent was left 3mo in place.Clinical outcome was investigated 3mo after tube removal.RESULTS： Bicanalicular intubation method had higher complete and relative success rates compared to monocanalicular intubation（P =0.00）.In addition,Monoka intubation had better outcomes compared to Masterka technique（P =0.046）.No difference was found between genders but the higher the age,the better the outcomes with bicanalicular technique rather than monocanalicular.CONCLUSION： Overall success rate of bicanalicular intubation is superior to monocanalicular technique especially in older ages.Also,based upon our clinical outcomes,Masterka intubation is not recommended in cases of failed probing.

Use of the Crawford tube for symptomatic epiphora without nasolacrimal obstruction

AIM： To evaluate the effectiveness of the Crawford tube in treating symptomatic epiphora without nasolacrimal obstruction. METHODS： A protocol was adopted for the management of symptomatic epiphora without nasolacrimal obstruction. Patients who suffered symptomatic epiphora without nasolacrimal obstruction in both eyes were included in the study. One eye was treated with Crawford tube intubation and the other eye was treated with medication therapy. Degree of watering, patient satisfaction, and symptomatic improvement were carefully evaluated by one of the authors at the end of the follow-up period, after Crawford tube removal, to ascertain functional results. RESULTS： Thirty-seven adult patients （37 eyes） underwent Crawford tube intubation for functional epiphora. The mean follow-up time after removal of the tube was 14.8 ~4.8mo. The procedure was an overall success in 28 eyes （75.7%）, with symptoms improving significantly. Two eyes （5.4%） were relieved of indoor epiphora, two （5.4%） had minimal epiphora outdoors, but only with wind or cold, and five （13.5%） continued to experience tearing both indoors and outdoors. Thirty of the patients （81%） expressed satisfaction with the procedure. CONCLUSION： Crawford tube insertion is an effective, safe, simple, and relatively noninvasive treatment strategy for functional lacrimal system obstruction.

Laser-assisted dacryocystorhinostomy in nasolacrimal duct obstruction：5-year follow-up

AIM：To evaluate the long-term sucess rate of laserassisted dacryocystorhinostomy （L-DCR） in patients with nasolacrimal duct obstruction （NDO）.METHODS：Forty-one eyes of forty patients aged between 21-85y （mean 56.7y） who underwent L-DCR for the treatment of NDO were included in this retrospective,non-randomized study. The follow-up time was 72mo.Functional sucess was defined as the disappearance of epiphora under normal conditions and the presence of a patent ostium on lacrimal irrigation. Anatomical success was defined as a patent lacrimal passage on syringing besides continuing epiphora. Surgical failure was defined as persistent epiphora and closed ostium.RESULTS：Twenty-seven of 40 patients （67.5%） were female and 13 of 40 patients （32.5%） were male. The NDO was right-sided in 17 （42.5%） patients and left-sided in 22（55%） patients whereas 1 （2.5%） patient had undergone bilateral surgery. In 11 （27.5%） patients there were additional nasal abnormalities requiring simultaneous surgical approach. The average time for L-DCR was 26.50±4.9min（16-39min） and the average total amount of laser energy used was 287±27.9 J （239-367 J）. At the 5y follow-up, anatomical sucess rate was 75.0%（30 patients） and functional success rate was 65.0%（26 patients）, whereas surgical failure was seen in 25%（10 patients）. Revision of surgery was performed in 10 cases （25.0%）; failure of revision surgery was seen in 2 cases（5.0%）.CONCLUSION： Transcanalicular L-DCR is a reliable and fast procedure in the treatment of NDO. It can be alternative to external DCR which is accepted as the gold standard currently. The functional and anatomical success rate is higher in the first months and years, but still satisfactory at fifth year.

Mode of delivery, birth weight and the incidence of congenital nasolacrimal duct obstruction

AIM: To study any possible association of congenital nasolacrimal duct obstruction(CNLDO) with mode of delivery, birth weight and gestational age. METHODS: We retrospectively reviewed charts of all patients(n=2591) under the age of 3 y who were born between April 2015 and May 2017 and were examined at the Ophthalmology Clinic of Emsey Hospital Istanbul, Turkey. We identified patients(n=105) who were diagnosed as CNLDO. The mode of delivery, birth weight and gestational age along with any adverse event during or after delivery or any other health history were determined. Birth statistical data were obtained from the hospital’s medical records database. RESULTS: Gestational age of babies who were born via cesarean section(CS) was lower than gestational age of babies who were born via normal spontaneous vaginal delivery(NSVD;P=0.002). Babies who were born via CS were found to have 3.75 times higher risk of developing NLDO when compared to babies who were born via NSVD(OR=3.754). CONCLUSION: There is a possible association between CS and CNLDO.

Measuring nasolacrimal duct volume using computed tomography images in nasolacrimal duct obstruction patients in Korean

AIM: To investigate nasolacrimal duct(NLD) volume in Korean patients and to examine the correlation between NLD volume and obstruction. METHODS: Of patients who underwent orbital computed tomography from March 2013 to January 2016, patients diagnosed with NLD obstruction were classified into the patient group and patients without obstruction were classified into the control group. The NLD volume was measured using the Image J program, which showed the NLD in axial,coronal, and sagittal images on computed tomography. RESULTS: The average value of men's NLD volume,265.33±90.57 mm3, was significantly larger than women's,211.87±68.61 mm3(P=0.009). In the patient group, the NLD volume of the obstructed eyes, 242.49±82.93 mm3,and the non-obstructed eyes, 225.20±73.20 mm3, were significantly higher than the control group, 217.61±82.04 mm3(P<0.001, P<0.001). CONCLUSION: The NLD volume is larger in men than in women in Korean adults. If there is NLD obstruction in women, the NLD volume is larger and it is judged that inflammatory reaction caused a chronic change in the bone around the NLD and affect the measurement of NLD volume.

Comparison of scanning electron microscopy findings regarding biofilm colonization with microbiological results in nasolacrimal stents for external, endoscopic and transcanalicular dacryocystorhinostomy

AIM:To compare bacterial biofilm colonization in lacrimal stents following external dacryocystorhinostomy(EX-DCR),endoscopic dacryocystorhinostomy(EN-DCR),and transcanalicular dacryocystorhinostomy(TC-DCR)with multidiode laser.METHODS:This prospective study included 30consecutive patients with nasolacrimal duct obstruction who underwent EXT-,EN-,or TC-DCR.Thirty removed lacrimal stent fragments and conjunctival samples were cultured.The lacrimal stent biofilms were examined by scanning electron microscopy(SEM).RESULTS:Eleven(36.7%)of the 30 lacrimal stent cultures were positive for aerobic bacteria(most commonly Staphylococcus epidermidis and Pseudomonas aeruginosa).However anaerobic bacteria and fungi were not identified in the lacrimal stent cultures.Twenty-seven(90%)patients had biofilmpositive lacrimal stents.The conjunctival culture positivity after the DCR,biofilm positivity on stents,the grade of biofilm colonization,and the presence of mucus and coccoid and rod-shaped organisms did not significantly differ between any of the groups(P】0.05).However,a significant difference was found when the SEM results were compared to the results of the lacrimal stent and conjunctival cultures(P【0.001).CONCLUSION:Type of dacryocystorhinostomy(DCR)surgery did not affect the biofilm colonization of the lacrimal stents.SEM also appears to be more precise than microbiological culture for evaluating the presence of biofilms on lacrimal stents.

Computed tomography imaging features for amyloid dacryolith in the nasolacrimal excretory system:A case report

BACKGROUND Nasolacrimal duct obstruction leading to epiphora is a common ophthalmologic complaint,and it may derive from amyloidosis in rare cases.There are a few reports about localized amyloidosis,and amyloidosis with involvement and obstruction of the nasolacrimal duct is exceedingly rare.CASE SUMMARY A 54-year-old male presented with a 2-year history of a lump overlying the left lacrimal sac that had grown rapidly for nearly half a year.Physical examination touched a firm lump in the left lacrimal sac.Nasal endoscopy discovered lesions in appearance of sediments with easy bleeding at the entry of the nasolacrimal duct of the left inferior nasal meatus.Computerized tomography scan revealed speckle high density in the left lacrimal sac and the dilated nasolacrimal duct.During an endoscopic exploration and excision,a large number of dacryoliths were exposed.Pathology indicated amorphous pink material and multinucleated giant cell reaction in the fibrous tissue.CONCLUSION This case showed amyloidosis in localized form mimicking dacryolith with nasolacrimal duct obstruction.In clinical practice,we should be aware of the possibility of localized amyloidosis in the nasolacrimal excretory system.

Ocular Findings in Trisomy 13: Nasolacrimal Duct Stenosis Case Series

Trisomy 13, also known as Patau Syndrome, is a congenital malformation that leads to several ocular anomalies, of which cataracts are the most common, as well as iris and retinal colobomas, persistent hyperplastic primary vitreous, persistent tunica vasculosa lentis, and microphthalmos. While most do not survive beyond the neonatal period, those that do survive past one year of age have an 84% chance of making it to age 5. Therefore, treatments for ocular problems should be used to improve the quality of life if the child can withstand surgery. The literature on this topic has described histopathologic findings in postmortem eyes. This case series supports those observations and presents a new discovery of nasolacrimal duct obstructions or stenosis. Deciding on surgical intervention in cases with Trisomy 13 can be challenging, and a variety of factors must be taken into account before surgery is considered. Treatment of these cases can be difficult, necessitating deliberate consideration and determination on a case-by-case basis;however, this case series gives additional evidence to help guide these decisions. Traditionally, trisomy 13 was regarded as being lethal, multiple organ malformations and severe intellectual disability.

Practice patterns among ophthalmic surgeons in treating concomitant oculoplastic conditions in preoperative period:A questionnaire-based study

BACKGROUND Addressing oculoplastic conditions in the preoperative period ensures both the safety and functional success of any ophthalmic procedure.Some oculoplastic conditions,like nasolacrimal duct obstruction,have been extensively studied,whereas others,like eyelid malposition and thyroid eye disease,have received minimal or no research.AIM To investigate the current practice patterns among ophthalmologists while treating concomitant oculoplastic conditions before any subspecialty ophthalmic intervention.METHODS A cross-sectional survey was disseminated among ophthalmologists all over India.The survey included questions related to pre-operative evaluation,anaesthetic and surgical techniques preferred,post-operative care,the use of adjunctive therapies,and patient follow-up patterns.RESULTS A total of 180 ophthalmologists responded to the survey.Most practitioners(89%)felt that the ROPLAS test was sufficient during pre-operative evaluation before any subspecialty surgery was advised.The most common surgical techniques employed were lacrimal drainage procedures(Dacryocystorhinostomy)(63.3%),eyelid malposition repair(36.9%),and ptosis repair(58.7%).Post-operatively,47.7%of respondents emphasized that at least a 4-week gap should be maintained after lacrimal drainage procedures and eyelid surgeries.Sixty-seven percent of ophthalmologists felt that topical anaesthetic procedures should be preferred while performing ocular surgeries in thyroid eye disease patients.CONCLUSION Approximately 50%of ophthalmologists handle prevalent oculoplastic issues themselves,seeking the expertise of an oculoplastic surgeon under particular conditions.Many ophthalmologists still favor using ROPLAS as a preliminary screening method before proceeding with cataract surgery.Eyelid conditions and thyroid eye disease are not as commonly addressed before subspecialty procedures compared to issues like nasolacrimal duct obstruction and periocular infections.

Endonasal Endoscopic Dacryocystorhinostomy with the Use of Radiofrequency (RF) Surgical Technique

Endonazal endoscopic dacryocystorhinostomy (DCR) with radiofrequency (RF) surgical technique is a procedure selected for nasolacrimal duct obstruction and chronic dacryostenosis in the setting of patent canaliculi and a functional lacrimal pump. Two major approaches are utilized: external, via a transcutaneous incision and endonasal endoscopically guided. The surgery has the high success rate via both approaches. We review the history, evolution, current techniques, complications and future directions of DCR radiofrequency RF operative technique. The modified endonasal RF-coagulation technique was performed in patients aged 18 - 85 (women-80, men-35) from 2017 to 2023. All patients suffered from chronic dacryocystitis. They had been administered the course of traditional conservative treatment and were provided with the ophthalmologist’s and otorhinolaryngology’s consultations prior to the surgery. In order to verify the diagnosis, the patients were conducted the CT-scan examination of nasal cavity and paranasal sinuses as well as the endoscopy of nasal cavity. Endonasal dacryocystorhinostomy with RF coagulator proved to be effective in 80% of patients;Over 3 - 4 years following the surgery, the recurrence was manifested in 8 patients after 6 months and in 12 patients, after a year. The above mentioned surgical treatment is administered by minimally invasive surgical method. At the same time, the long-term, for about 1 year, implantation of silicone drainage in the nasolacrimal ducts significantly reduces the risk of recurrence. At the present stage, the endoscopic Endo-DCR surgery is being improved, and the diverse treatment methods, including radiofrequency (RF) in endonasal endoscopic microsurgical techniques, are being studied and introduced into practice.

Pediatric nasolacrimal duct obstruction-benefit of a combined therapeutic approach

Background:Pediatric nasolacrimal duct obstruction (PNDO) requires therapeutic intervention after conservative procedures failed.As resilient treatment guidelines for the treatment are missing,the aim of this study was to evaluate the advantages of two different intervention techniques in children with PNDO.Methods:Between January,2006 and June,2014,233 children (0-208 months) were treated either with conventional probing by ophthalmologists only (Group I) or with endonasal endoscopic interdisciplinary approach (Group Ⅱ).The clinical outcome was analyzed.Results:The overall success rate of Group Ⅰ was 93.4% compared to 98.4% of Group Ⅱ (P<0.05).50% of all interventions (n=62) of Group Ⅱ required further surgical procedures in addition to probing/irrigation,particularly with regard to children <6 and >24 months.Conclusions:Endoscopic control in treatment of PNDO allows exact identification of the stenosis and appropriate surgical intervention with an improved clinical outcome.Endonasai endoscopic surgical techniques should be the standard PNDO treatment.

Localized amyloidosis affecting the lacrimal sac managed by endoscopic surgery:A case report

BACKGROUND Here we present a rare case of localized amyloidosis involving the nasolacrimal duct and lacrimal sac which was managed by endoscopic surgery.CASE SUMMARY A 50-year-old man whose medical history included bilateral ventricular fold and vocal cord amyloidosis complained of bilateral epiphora.Magnetic resonance imaging revealed a neoplasm within the nasolacrimal sac.Characteristic positivity for Congo red staining and birefringence under a polarized microscope proved the diagnosis of amyloidosis.Dacryocystorhinostomy via an endoscope obtained a favorable result.A one-year follow-up found no recurrence.CONCLUSION There are few reports on amyloidosis involving the lacrimal outflow system,and management and outcome are not clear.Endoscopic dacryocystorhinostomy can be a choice to relieve symptoms.Regular follow-up and monitoring of systemic diseases are highly recommended.

鼻泪管平滑肌瘤1例

1临床资料 患者,女性,50岁。间断性右侧鼻痛5年余,逐渐加重。无明显诱因,发作时可放射至右侧上颌部,并间断出现右侧溢泪,不伴脓性分泌物,无鼻堵、脓涕和涕中带血,无嗅觉减退及鼻腔异味,无面部麻木、复视等症状。外院行泪囊造影示右侧鼻泪管堵塞。鼻窦CT示右侧鼻泪管内软组织密度影，下端突入右侧下鼻道。

Endoscopic vs external dacryocystorhinostomy-comparison from the patients' aspect

·AIM: To compare the success and complication rates,duration of surgeries and clinical comfort after endoscopic dacryocystorhinostomy(END-DCR) or external dacryocysto-rhinostomy(EXT-DCR).·METHODS: Fifty patients who underwent EXT- or END-DCR between January 2010-2012 were involved in the study. A questionnaire was applied to patients preoperatively, and postoperatively. Subjective success was defined by absence of epiphora, objective success by a normal nasolacrimal lavage and a positive functional endoscopic dye test(FEDT). Postoperative pain and cosmetic result of surgery were interpreted by the patients, who were also asked whether they would offer this surgery to a friend or would prefer this surgery once more if necessary.·RESULTS: Twenty-five patients underwent END-DCR and 25 underwent EXT-DCR. Mean duration of surgeries were 35 min both for EXT-DCR(30-50) and END-DCR(35-50)(P =0.778). Intraoperative bleeding were documented in 48% of EXT-DCR and 4% of END-DCR cases(P 【0.001). In total 96% of EXT-DCR and 100% of END-DCR patients had subjective success. Objective success was 100% in each group. There was no significant difference between the epiphora scorings and FDDT results in postoperative visits among the groups.END-DCR group reported less pain in first week and month(P 【0.05, P 【0.05). More patients in END-DCR group were happy with the cosmetic result in first week and month(P 【0.001, P 【0.001). More patients in END-DCR group offered this surgery to a friend(P 【0.001). All patients in END-DCR group preferred this surgery once more if necessary, only 48% in EXT-DCR preferred the same method(P 【0.001).·CONCLUSION: Although both END- and EXT-DCRs provide satisfactory outcomes with similar objective andsubjective success rates, we demonstrated that the endonasal approach caused significantly less pain in early postoperative period than the external approach.Clinical comfort defined by the patients was quite higher in END-DCR group, in which patients mainly were pleased to encounter a sutureless surgical area.

Cosmetic evaluation of surgical scars after external dacryocystorhinostomy

AIM： To evaluate the surgical scars of external dacryocystorhinostomy （DCR） cosmetically. METHODS： Totally 50 consecutive cases of primary acquired nasolacrimal duct obstruction （PANDO） were included in the study. Surgical scars were assessed by the patients and two independent observers at 2, 6 and 12wk postoperatively on the basis of visibility of the scars and still photographs respectively and were graded from 0-3. Kappa test was utilised to check the agreement of scar grading between the two observers. Wilcoxan signed ranks test was used to analyse the improvement of scar grading.RESULTS： Thirty-four （68%） patients graded their incision site as very visible （grade 3） at 2wk. At 6 and 12wk, incision site was observed as grade 3 by 7 （14%） and 1 （2%） patients respectively. Photographic evaluation of patients by 2 observers showed an average score of 2.75, 1.94 and 0.94 at 2, 6 and 12wk respectively. Change in scar grading from grade 3 to grade 0 in consecutive follow-up （2, 6 and 12wk） was found to be highly significant both for the patient as well for the observers （P〈0.0001）.CONCLUSION： The external DCR is a highly effective and safe procedure and in view of low percentage of cases who complained of marked scarring in the present study, thus scarring should not be the main ground for deciding the approach to DCR surgery, even in young cosmetically conscious patients.

Primary non hodgkin's lymphoma of lacrimal sac presented as recurrent acute dacryocystitis: A case report

Primary non Hodgkin's lymphoma of the lacrimal sac is uncommon but potentially delay in diagnosis as it may mimic the presentation of primary post saccal nasolacrimal duct obstruction. In this article, we reported a case of primary non Hodgkin's lymphoma of the lacrimal sac presented with recurrent acute dacryocystitis in a young lady. A 28 years old Malay lady had history of persistent epiphora on left eye for 4 years. Prior to presentation to our clinic, it was preceded by progressive recurrent painful medial canthal swelling for 6 months duration. Clinical diagnosis of post saccal naso lacrimal duct obstruction was made and otorhinolaryngology assessment revealed intranasal mass. Endoscopic excision was done showed diffuse large B cell lymphoma on histology. The patient was started on 6 cycles of chemotherapy which subsequently result in no recurrence of the tumour post chemotherapy. Any case of post saccal nasolacrimal duct obstruction should be investigated thoroughly as it may become as a presentation of other sinister pathology.

Comparison of the extrusion rate of Crawford tubes

· AIM: To compare the outcomes of dacryocystorhinostomy(DCR) using traditional Crawford tubes(TCT) and Crawford tubes with suture(CTS) in the lumen.· METHODS: Retrospective case series consisting of patients who underwent DCR between 2008 and 2013.·RESULTS: A total of 61 DCRs were performed on 50 patients. Patients who underwent DCR using CTS had higher rates of prolapse compared to the TCT group(50% vs 9.4%; P =0.003). Stent removal occurred earlier in patients who received CTS(3.3mo vs 5.1mo; P =0.004). Success rates were equivalent between the two groups(75% vs 81.1%; P =0.684).·CONCLUSION: CTS in the lumen increases the risk of prolapse, prompting earlier tube removal in patients following DCR for nasolacrimal duct obstruction(NLDO).Earlier removal of tubes does not appear to significantly decrease success rates.